The Patient-Reported Outcomes Measurement Information System (PROMIS) initiative aims to develop and disseminate core patient-reported items banks across a wide taxonomy of biopsychosocial illness experiences. Although the current PROMIS taxonomy is expansive, it does not yet include items pertaining to gastrointestinal (Gl) Distress. Our objectives are to first develop a Gl Distress domain using the rigorous standards established by the PROMIS network, and then to test the resulting items in 3 distinct patient populations with Gl distress: (1) irritable bowel syndrome (IBS), (2) inflammatory bowel disease (IBD), and (3) systemic sclerosis (SSc) at 4 large Medical Centers. Our UOl has 2 specific research aims: 1) To develop a Gl Distress item pool by: (a) developing an initial Gl Distress item pool by identifying extant items in the literature, removing redundant and vague items, and revising chosen items to reach uniformity, and (b) expanding the initial pool and establishing content validity by conducting focus groups and cognitive interviews of patients in three patient groups: IBS, IBD, and SSc. 2) To evaluate the psychometric properties of the Gl Distress item pool by: (a) evaluating the dimensionality of the Gl distress item pool and assessing fit of item response theory models in 3 samples of 500 patients with IBS, IBD, and SSc (n=1500 overall), (b) evaluating the associations of the Gl Distress domains with health-related quality of life legacy instruments for Gl illness and with symptom severity, and (c) evaluating the responsiveness and estimating the minimally important differences for the Gl Distress domains. To achieve these aims, we have convened a team of clinicians with expertise in assessing PROs, experts in PRO item development and evaluation, and experts in item response theory. The narrative describes our evolving conceptual framework for Gl Distress, reviews preliminary data from our group regarding PRO measurement in Gl disorders, emphasizes our past experience using PROMIS. PUBLIC HEALTH RELEVANCE: Gl disorders engender an extraordinary burden of illness in the United States. This burden includes the high population prevalence, overwhelming costs of care, and the large impact of Gl disorders on health-related quality of life (HRQOL). Moreover, the Gl-specific rate of health care visits rose by 20 percent between 2000-2004. Given the significant burden of illness of Gl disorders, coupled with the over-representation of many Gl disorders in women, it is vital that the PROMIS taxonomy expand to include items pertaining to Gl Distress.